Method of making 1-phenyl-2-3-dimethyl-4-dimethylaminopyrazolone.



Im rovements 1 henyl 2.3 Dimethyl 4 Dimethyl- EMIL SGHEITLIN, OF ALTSiETTEN, NEAR ZURICH, SWITZERLAND.

METHOD OFKMAKING 1-PH'ENYL-2.PDIMEi'IHYL-4-DIMETHYLAMINOPYRAZOLONE.

Specification of Letters Patent.

Patented Aug. 3, 1909.

Application filed August 28, 1907. 7 Serial No. 390,477.

To all whom it may concern:

Be-it known that I, EMIL ScnEIT-LIN, a citizen of the Republic of Switzerland, re-

siding at Altstetten, near Zurich, Switzerland, have invented certain new and useful in Methods of Making amino yrazolonc; and I do hereby declare the fol owing to be a full, clear, and exact description of the invention, such. as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to the production of 1 phenyl dimethyl 4 dimethylaminopyrazolonc and has for-its object to produce the same pure and directly, without the formation ol'by products and. its subsc- E adhering to the suit-amino compound. to fur-.

qucnt tedious separation therefrom. p

I have found that ];-phenyl-2.3-dimethyl- 4-dirhcthyl amino-pyrazolone can be readily obtained by reacting with dimethyl-srillate upon l-phenyl-Z.3-diincthyl 4 sulf aminopyrazolone. The advantages of this method over the usual method of procedure which consists in rnethylating l-phenyl-ZB-dimethyl 4 'amino pyrazolone lies in the readiness with which the reaction takes place with the 1 phenyl 2.3 diincthyl 4- sultamino-pyrazolone and the great unity with which the product can be obtained without tedious and expensive separation or treatment. It is important that in the methylating, pure starting materials be used and much depends thereon for the ready reaction. The materials heretofore used as starting materials 2'. c. 1 )henyl 2.3- dimethyl-4-amino-pyrazolone eft much to be desired in this respect, as it could be obtained pure only by means of costly round-' about methods and further that it altered in time. Another advantage of the present process is that the result of the. reaction is etter than in other processes.

In methylating 1-phenyl-2.3-dirhethyl-4- amino-pyrazolone by means of dimethylsulfate the reaction takes place very violently so that it is necessary to verycarefully add the methylating material in small quantities and even when this is done very slowly there 'tre formed to some extent quarternary ainmcnium combinations to which the violence of the reaction is attributed. By the use of l phenyl 2.3 dimethyl 4 sull aminopyrazolone the reaction first takes place at a r se of temperature which can readily be regulated until the endof the reaction and the formation of by products'does not take place and the reaction proceeds more nearly in accordance with the theory. The reaction is believed to take place as follows-- Although it is desirable to use alcohol as a solvent, the reaction may be accomplished Without it, there'being suihcient moisture nish a molecule of water. The reaction may then be expressed as follows:-

In place of (Ii-methyl sulfate any other suitable niethylating substance may be used, such, for example, as methyl-iodid, chlorid and bromid, but I prefer the methyl-sulfate on account 'of its cheapness. And the reaction without any solvent whatever is pre sumed to be as follows, the two substances, however, being vigorously stirred The S0 is, however, not set free, and what becomes of it and how it combines is not known.

For example to 284 parts of 1-phenyl-2.3- dimethyl-4-sulf-amino-pyrazolone first add 46 parts of alcohol and 252 parts of dimethylsulfate. The mixture is heated from 110 to 115 centigrade'and kept at this temperature from three to four hours, the melted product is dissolved in water, made alkaline ,no residue upon eva oration; In

with sodium or potassium hydrate, and'the 1- phenyl 2.3 dimethyl 4 dimethyl aminopyrazolone obtained from the solution by means of benzol. By crystallizing the same from its aqueous solution or from its benzol solution, a perfectly pure roduct is obtained. The treatment with enzol in order to separate the product is as follows. A quantity of benzol is added to the alkaline solution. The benzol floats in a layer thereon, the whole is shaken and the product dissolves in the benzol. The shaken mixture is allowed to stand and the benzol decanted or otherwiseseparated. This operation is repeated-until a sample of the benzolleaves ractical operations three or ourtimes-will e suffiwent.

I claim:- 1. In the method of making. 1-phenyl-2.3-

dimethyl-4-dimethyl-amino pyrazolone, re-

acting upon 1'-phenyl-2.3-dirrrelzhyl-4-sulfaminoyrazolone at'a temperature above norma by a substance capable of methylating the same. V v

2. In the method of making 1 phenyl-2.3 dimethyl-4-dimethyl-amino-pyiazolone, reacting upon 1-phenyl-2.S-dimthyl-4-sulf amino-pyrazolone with dimethylsulfate at 'an elevated temperature until the reaction is complete.

3. The method of making 1-phenyl-2.3- dimethyl 4 dimethyl amino -pyrazolone, which consists in mixing 1-phenyl-2.3 -di-' methyl-4-sulf-amino-pyrazolone with aloo- 1101, reacting thereon with dimethyl-sulfate at a temperature between and centigrade, extracting the 1 -phenyl 2.3 dimethyl 4 dimethyl amino pyrazolone by means of a suitable solvent, and crystallizing the product therefrom. v

4. The method of making l-phenyl-2.3- dimethyl 4 dimethyl amino pyrazolone, which consists in mixing 1-phenyl-2.3di methyl 4-sulf amino pyrazolone with solvent, reacting thereon with dimethyl-sulfate at a temperaturexbetween 110 and 115 centigrade, extracting the 1-phenyl-2.3-di methyl 4 dimethyl amino pyrazolone by means of a suitable solvent, and crystalliz- 

